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The Effect of Surface Roughness on the Extinction Spectra and Electromagnetic Fields around Gold Nanoparticles

Published online by Cambridge University Press:  01 February 2011

Shuzhou Li
Affiliation:
li@northwestern.edu, Northwestern University, Department of Chemistry, 2145 Sheridan Rd, Evanston, IL, 60208, United States
George C. Schatz
Affiliation:
schatz@chem.northwestern.edu, Northwestern University, Department of Chemistry, 2145 Sheridan Rd,, Evanston, IL, 60208, United States
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Abstract

Electromagnetic enhancement arising from plasmon resonance excitation plays a major role in surface-enhanced Raman spectroscopy (SERS), and as a result nanoparticle morphology can significantly affect SERS intensities. In this paper we have calculated these enhancements as well as extinction spectra using the discrete dipole approximation for a system consisting of a dimer of gold disks that is made using on-wire lithography. Including surface roughness in the calculations leads to SERS enhancements for the disks whose dependence on disk spacing and thickness is in agreement with experimental measurements, with a maximum enhancement when the thickness of the disk and the disk-disk gap are 100 nm and 32 nm, respectively. These results are in better agreement with experiments than earlier estimates based on flat surfaces.

Type
Research Article
Copyright
Copyright © Materials Research Society 2008

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